LinkedListSwapPairs.java

package Codes;

import java.util.Scanner;

public class LinkedListSwapPairs {
    static Node head;
    static class Node{
        int data;
        Node next;
        Node(int d){
            data=d;
            next=null;
        }
    }
    static void append(int d){
        Node newnode=new Node(d);
        if (head==null)
            head=newnode;
        else {
            Node temp=head;
            while (temp.next!=null){
                temp=temp.next;
            }
            temp.next=newnode;
        }
    }
    static void display(){
        Node temp=head;
        while (temp!=null){
            System.out.print(temp.data+"->");
            temp=temp.next;
        }
    }
    static void swap(){
        Node one=head;
        while (one!=null && one.next!=null){
            int temp=one.data;
            one.data=one.next.data;
            one.next.data=temp;
            one=one.next.next;
        }
    }
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        String input=sc.nextLine();
        String[] arr=input.split(" ");
        for (int i=0;i<arr.length;i++){
            append(Integer.parseInt(arr[i]));
        }
        display();
        System.out.println("NULL");
        swap();
        display();
        System.out.println("NULL");
    }
}